The present invention relates to a method for checking various function states in a key telephone system by using indicators provided in respective key telephones for indicating states of subscriber lines and extension lines.
Nowadays, in a key telephone system composed of a central control equipment and a plurality of key telephones or extension telephones, to each key telephone can be preset various additional functions such as the assignment of incoming ringing, the assignment of alarm sound, the assignment of extension simultaneous ringing, i.e. all call, the assignment of door-phone ringing and so on. As for a method for setting various additional functions mentioned above, there has been proposed two methods, one is to effect the setting operation mechanically by means of short-circuit pins, DIP (Dual Inline Package) switches, etc. arranged in the central control equipment, and the other is to effect the setting operation by storing information for denoting the additional function allocated to respective telephones into a memory device arranged in the central control equipment under the control of a program terminal connected to the central control equipment.
After setting, the states representing the preset additional functions of each key telephone must be checked in a manner mentioned below.
In the example of performing the function setting operation mechanically, it is necessary to check visually positions of the short-circuit pins or the DIP switches in the central control equipment, and then to confirm whether the preset functions are performed correctly or not by actually operating keys of the key telephone according to each additional functions one by one. This checking confirmation requires a very long time and is quite cumbersome, because this operation must be done both on the central control equipment side and the key telephone side. When the number of the functions valid for setting and also the number of the key telephones in the system are large, the above drawbacks become manifest.
Even in case of storing the function setting information in the central control equipment, it is necessary to confirm whether the additional functions have been correctly preset in the central control equipment or not by actually operating the keys according to the functions one by one on the key telephone side, and thus the checking operation requires also a very long time.